Method of making a laminated photographic light-sensitive element

ABSTRACT

A METHOD FOR COATING BOTH SURFACESS OF A SUPPORT SUITABLE FOR PHOTOGRAPHIC LIGHT-SENSITIVE ELEMENTS WHEREBY ONE OR MORE COATING COMPOSITIONS ARE APPLIED TO CONTINUOUSLY MOVING SURFACES OF COOLING MEMBERS, GELLING SAID COATINGS BY COOLING, STRIPPING THE GELLED LAYERS FROM THE COOLING SURFACES AND ADHERING THEM TO THE SURFACES OF THE SUPPORT.

Feb. 2, 1971 TAKESHI MKAMI METHOD OF MAKING A LAMINATED PHOTOGRAPHICLIGHT SENS IT IVE ELEMENT Filed Dec. 28, 1967 FIG. I

INVENTOR TAKESHI MKAMI FIG. 2

ATTORNEYS United States Patent 3,560,288 METHOD OF MAKING A LAMINATEDPHOTO- GRAPHIC LIGHT-SENSITIVE ELEMENT T alreshi Mikami, Kanagawa,Japan, assignor to Fuji Photo Film (10., Ltd., Kanagawa, Japan FiledDec. 28, 1967, Ser. No. 694,180 Claims priority, application Japan, Dec.28, 1966, 42 438 Int. Cl. B29c 23/00 [1.5. CI. 156-229 6 Claims ABSTRACTOF THE DISCLOSURE A method for coating both surfaces of a supportsuitable for photographic light-sensitive elements whereby one or morecoating compositions are applied to continuously moving surfaces ofcooling members, gelling said coatings by cooling, stripping the gelledlayers from the cooling surfaces and adhering them to the surfaces ofthe support.

BACKGROUND OF THE INVENTION The present invention relates to a method ofcoating opposite sufaces of a support for preparing photographiclight-sensitive elements. More particularly, the invention relates to amethod of coating the opposite surfaces of a support for photographiclight-sensitive elements in which two or more photographic layers suchas silver halide emulsion layers and protective layers are applied toone surface of the support and, at the same time, one or more layerssuch as a backing layer are applied to the opposite surface of thesupport. Subsequently, according to the invention, the layers thusapplied are dried simultaneously.

As a method of coating the opposite surfaces of a continuouslytravelling support, there has previously been employed a method wherebyone or more coating compositions are applied to one surface of a supportfollowed by drying and, thereafter, one or more coating compositionsapplied to the opposite surface thereof followed by drying. A method hasalso been proposed whereby the opposite surfaces of a support are coatedin one step and, thereafter, the layers on the opposite surfaces driedsimultaneously. The latter method is preferred over the former becauseof better operation efficiency and economy.

In the previously proposed methods wherein the opposite surfaces of asupport are coated in one step and thereafter dried simultaneously, thesurfaces of the support are generally coated with coating compositionsin sol-like states by means of coating devices. In these cases, wherethere is employed a technique of directly applying coating sols to asupport, such as by dip coating, doctor coating, bead coating, and thelike, the overall coating speed is limited by the side of the supporthaving the lower coating speed, the amount of coating, the dryingcapacity of the system, the properties of the various coatingcompositions, and the coating conditions. Hence it is difficult to applyprecisely and with a high degree of speed coating compositions to thesupport having a high concentration and a high viscosity in thin layers.

Furthermore, where sol-like coating compositions are coated on oppositesurfaces of a support in one step, there have been employed methodswherein both surfaces are coated with the coating compositionsseparately and methods wherein both surfaces are coated with themsimultaneously. However, in the former method, since just after coatingone surface of the support another surface thereof must be coated with acoating composition without contacting the coated layer to foreignmaterials such as solid walls, etc., it is difficult to obtain uniformthicknesses of coatings and good coating qualities.

Also, in methods of applying sol-like coating compositionssimultaneously to the opposite surfaces of a support, at the same level,e.g., a method in which both surfaces of the support are coatedsimultaneously with coating compositions by doctor coating devicespositioned at opposite sides of the support at the same level, the totalthicknesses of the whole layers coated may be constant. However, it isdifficult to obtain desired and uniform thicknesses of each layer on thesurface of the support and good coating qualities.

Therefore, an object of the present invention is to provide a coatingmethod for preparing photographic light sensitive elements in which bothsurfaces of a support are coated with coating compositions in one stepwhile improving the coating efficiency and reducing the coating cost.

Another object of this invention is to provide a method in which densecoating compositions for photographic light sensitive elements can beapplied precisely to oppo site surfaces of a support in thin layers inone step.

A further object of this invention is to provide a coating methodcapable of applying the aforesaid coating compositions to the oppositesurfaces of a support simultaneously in multiple layers.

BRIEF DESCRIPTION OF INVENTION The invention comprises applying coatingcompositions for photographic light sensitive element to the fiatcooling surfaces of continuously moving members positioned at theopposite sides of a continuously travelling support to provide thecooling surfaces uniform layers having desired thicknesses and layerstructures; gelling the layers thus applied; stripping the gelled thinlayers from the cooling surfaces of the moving members, and closelyadhering the layers thus stripped to the opposite surfaces of thecontiguous continuously travelling support.

DETAILED DESCRIPTION OF DRAWING The invention will be explained, more indetail, by referring to the accompanying drawing, in which;

FIG. 1 is a schematic cross sectional view showing an embodiment of theinvention and FIG. 2 is a schematic cross sectional view showing anotherembodiment of the invention.

In FIG. 1, a support 1 to be coated, such as a film base or abaryta-coated paper, continuously travels through a space defined by thetwo cooling drums 8 and 8 having cooling surfaces 3 and 3 respectivelyand continuously rotating in the directions of the arrows. Coatingcompositions for photographic light-sensitive elements are applieduniformly to the cooling surfaces 3 and 3' by means of coating devices 2and 2 such as by extrusion hoppers or slide hoppers in thin layershaving desired layer structures. The coating compositions thus appliedto the cooling surfaces 3 and 3' are immediately cooled to form gelledthin layers 4 and 4. The thin layers 4 and 4' of the coatingcompositions thus gelled come into contact with the continuouslytravelling support 1 at the contact points 6 and 6 where the layers areclosely adhered to the support. In this case, the support may travelwith a speed identical to or faster than that of cooling surfaces 3 and3'. In the case where the support travels faster than the speed of thecooling surfaces, the thin layers 4 and 4' are stretched at stretchingpoints 5 and 5 to provide thinner layers 7 and 7. For example, if thespeed of the support is 3 times as fast as the speed of the coolingsurfaces, the thickness of the layers is reduced to about /3 of thethickness of the original layers. The cooling surfaces 3 and 3 of thecooling drums 8 and 8' are composed of such material that the thinlayers 4 and 4 of the coating compositions are easily strippedtherefrom. The cooling surfaces of the cooling drums are suitablymaintained at a desired lower temperature by cooling from theirinteriors with av cooling medium for providing easily strippable cooledlayers of the coating compositions. The temperatures of the coolingsurfaces are determined by the kind of coating compositions, the coatingtemperature, the material comprising the cooling surfaces, etc. Forinstance, when a silver bromide emulsion is applied to a cooling surfaceplated wtih nickel at a temperature of 40 C., the gelled layer of thecoating composition can be easily stripped from the cooling surface at asurface temperature of 1l0 C. For improving the adhesiveness between thesupport 1 and the layers 7 and 7' of the gelled coating compositions,the support 1 or the surfaces of the layers 4 and 4' of the gelledcoating compositions to be adhered to the support may be preliminaryheated by high frequency heating, infrared heating, or by blowing withhot air. Moreover, air pressure may be applied to the gelled andstretched layers at the stretching portions 5 and 5' to press the layersof the coating compositions to the travelling support, whereby theadhesive properties of the support 1 and the layers 7 and 7 of thecoating compositions are improved.

In the case where the support 1 travels with a high rate of speed, theremay be employed an apparatus capable of reducing the pressure of theatmosphere between the support 1 and the gelled layers of the coatingcompositions under stretching at the stretching portions 5 and 5' forpreventing the entrance of air between the gelled layers 7 and 7 of thecoating compositions and the support 1.

Moreover, it often happens that after stripping the gelled layers 4 and4' of the coating compositions, water is condensed on the coolingsurfaces 3 and 3' and accumulated in the spaces between the coatingdevices 2 and 2' and the cooling surfaces 3 and 3'. Hence the outletends of the coating device are cooled, and the coating compositionspartially gelled to prevent the coating compositions from being supplieduniformly. For overcoming this difficulty, there may be provided anapparatus for removing the water directly before the coatingcompositions are applied to the cooling surfaces 3 and 3' by means ofthe coating devices.

FIG. 2 shows an embodiment of the invention in which the coatingcompositions applied to the cooling surfaces of cooling drums aretransferred to a continuously travelling support separately. That is, asupport 1 travels continuously while supported by a roller 9 and aroller 10. In this case, the back surface of the support is contacted tothe roller surface 9 but the surface of the support having thereon alayer or layers of coating compositions is preventing from contactingthe roller 10 by, e.g., air blow or air cushion.

DETAILED DESCRIPTION OF INVENTION Thus, by the method of this invention,whole layers of coating compositions for photographic light sensitiveelements are applied to fiat and continuously moving cooling surfaces toprovide thereon the gelled films of the coating compositions and thelayers are stripped therefrom and adhered to the opposite surfaces of acontinuously travelling support, whereby the coating efficiency isimproved and the coating cost is reduced. Also, since the speed of themoving surfaces of the cooling members can be desirably varied in arange of 1% times the speed of the travelling support, dense and highlyviscous coating compositions can be precisely applied in thin layers andwith a high rate of speed to the opposite surface of a continuouslytravelling support without being limited by slower coating speeds dryingcapacity of the system and coating amounts.

Also, since in the method of this invention, the coating compositionsare applied to a travelling surface after being gelled on the coolingsurfaces of cooling members such as drums, the adverse elfects producedby the unevenness and the vibration of the continuously travellingsupport are lessened. The layer of the coating compositions are rapidlyset, and the formation of uneven surfaces can be prevented which is notthe case in the past where sol-like coating compositions were directlyapplied to the opposite surface of a support. Also, by the method ofthis invention, multiple layers of coating compositions having preciselayer constructions can be simultaneously formed on opposite surfaces ofa support when the gelled layers are transferred from the coolingsurfaces to the support at a same level.

The invention will be further explained by the following example.

EXAMPLE By using the apparatus shown in FIG. 2, both surfaces of anunder-coated film base were coated under the following conditions.

lst layer: silver bromide emulsion (70 cp. 2nd layer: silver bromideemulsion (50 cp.), and 3rd layer: aqueous gelatin solution (20 cp.).

The whole thickness of the aforesaid three layers was 300 microns on thecooling surface and microns after stretching.

Aqueous gelatin solution and dye (30 cps.)

The thickness of the above coating composition was 100 microns on thecooling surface and 100 microns after transferring to the support.

That is, the aforesaid three coating emulsions were applied in threelayers to the cooling surface of the rotary drum having a diameter of 50cm., and after setting by cooling, the layers thus formed weretransferred to a film base travelling at a speed of 20 m./min. whilestretching the layers to 3 times the thickness of the original layers.Thereafter, the coating composition for the back layer was applied tothe cooling surface and after setting, the layer thus formed wastransferred to the opposite surface of the film without stretching it,followed by drying immediately. By the procedure, a photographic lightsensitive film having emulsion layers and a back layer having uniformthickness and good qualities was obtained.

What is claimed is:

1. A method for preparing a photographic light-sensitive elementcomprising applying a uniform layer or layers of predeterminedthicknesses to each surface of a pair of continuously moving coolingmembers positioned at the opposite sides of a continuously travellingsupport, said layers comprising coating compositions where at least oneof said layers is a photographic light sensitive composition gelling thethus formed layers by cooling, strip ping the gelled layers from thesurfaces of said cooling members, and adhering the stripped layers tothe opposite surfaces of said continuously travelling support.

2. The method according to claim 1 wherein said stripped, gelled layersare heated to an elevated temperature to promote adhesion to saidsupport surfaces.

3. The method according to claim 1 wherein said layers gelled at thecooling surfaces are transferred to the continuously travelling supportsimultaneously.

6 4. The method according to claim 1 wherein said layers ReferencesCited gelled at the cooling surfaces are transferred to the con- UNITEDSTATES N S tinuously travelling support at separate positions. 3 032 8155/1962 Gerber 156 249X 5. The method according to claim 1 wherein saidsup- 3362866 1/1968 Zahn port travels at substantially the same speed asthat of 5 9/1968 igifjjil: 156 249X the surfaces of said coolingmembers.

6. The method according to claim 1 wherein said sup- BENJAMIN PADGETT,Primary Examiner port travels faster than the speed of the surfaces ofsaid 3, J LECI-IERT, J A i t t Examiner cooling members to stretch thelayers when they are trans- 0 U S Cl X R ferred from the coolingsurfaces to the opposite surfaces of the support

